You don't need to rely on an opinion; there's a fairly in-depth description of iOS security available direct from Apple: https://www.apple.com/ipad/business/doc

You don't need to rely on an opinion; there's a fairly in-depth description of iOS security available direct from Apple: https://www.apple.com/ipad/business/docs/iOS_Security_Oct12.pdf https://www.apple.com/ipad/business/docs/iOS_Security_Oct12.... My understanding is that files under iOS are grouped into various classes with different levels of protection. Some data is under a class for which the key is discarded when the device is locked; this requires the passcode to be entered again before access can be gained. Some data doesn't have full protection applied to it - for example, the phone must be able to display the name of a caller even when locked, so it's intuitively obvious that contact names/numbers can't have this applied. I'm not sure exactly what the scope of each class is, but Apple do claim to be enable to retrieve things like mail, and if the implementation is as they describe then I see a limited scope for backdoored encryption - obviously it's always possible, but none of the information they've released about capabilities is contradictory.